Medical-image processing apparatus and medical-image diagnostic apparatus

ABSTRACT

A medical-image processing apparatus and a medical-image diagnostic apparatus according to an embodiment include an acquisition unit, a generation unit, an identification unit, and a display control unit. The acquisition unit acquires a medical image containing a blood vessel collected by the medical-image diagnostic apparatus. The generation unit generates an anatomical structure model based on the medical image acquired by the acquisition unit. The identification unit identifies a position, on the medical image, of an index relating to blood flow analyzed through fluid analysis using the anatomical structure model. The display control unit displays the position of the index on the medical image, and also displays the index associated with the position of the index on the medical image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional Application of U.S. application Ser.No. 14/617,082, filed Feb. 9, 2015, which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2014-023740,filed on Feb. 10, 2014. The entire contents of the above-identifiedapplications are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a medical-imageprocessing apparatus and a medical-image diagnostic apparatus.

BACKGROUND

In recent years, coronary stenosis lesions have been diagnosed from bothaspects of “anatomical evaluation” of morphologically evaluating thepresence or absence of stenosis and the degree of the stenosis, forexample, and “physiological evaluation” of objectively evaluating thepresence or absence of myocardial ischemia and the degree of themyocardial ischemia, for example. As physiological indices used for the“physiological evaluation”, fractional flow reserve (FFR) and coronaryflow reserve (CFR), for example, are drawing attention. For example, theFFR is an index that indicates the degree of myocardial ischemia causedby stenosis of a coronary artery, and is represented by the ratio ofmaximum coronary blood flow in the presence of stenosis to maximumcoronary blood flow in the absence of stenosis. For example, the CFR isan index that indicates the ability to increase the coronary blood flowin response to the increasing demands of oxygen in a cardiac muscle, andis represented by the ratio of coronary blood flow during peak reactivehyperemia to coronary blood flow at rest.

These physiological indices have been conventionally calculated bycertain measuring devices. However, in these years, an analysistechnique is known in which the above-described physiological indicesare calculated based on analysis using image data containing bloodvessels. For example, CT-FFR is known in which an anatomical structuremodel (three-dimensional polygon model) of coronary arteries isgenerated from a CT image containing coronary arteries collected by anX-ray CT apparatus, and fluid analysis (computational fluid dynamics(CFD)) processing is applied to the generated three-dimensional polygon,whereby pressure distribution, blood velocity distribution, and FFRvalues, for example, in the coronary arteries are simulated to displaythese results on the three-dimensional polygon model. However, in theabove-described conventional techniques, it may be difficult to comparethe results of the fluid analysis with medical images.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining a configuration example of a systemincluding a medical-image processing apparatus according to a firstembodiment;

FIG. 2 is a diagram illustrating one example of configuration of themedical-image processing apparatus according to the first embodiment;

FIG. 3 includes diagrams illustrating one example of generation of a 3Dcoronary model by a 3D-coronary-model generating unit according to thefirst embodiment.

FIG. 4 includes diagrams for explaining one example of analysisperformed by a fluid analysis unit according to the first embodiment;

FIG. 5 includes diagrams illustrating one example of fusion imagesdisplayed on a display unit according to the first embodiment;

FIG. 6 is a flowchart illustrating the procedure of processing performedby the medical-image processing apparatus according to the firstembodiment;

FIG. 7 is a diagram illustrating one example of configuration of amedical-image processing apparatus according to a second embodiment;

FIG. 8 is a diagram illustrating one example of a fusion image displayedon a display unit according to the second embodiment;

FIG. 9 is a flowchart illustrating the procedure of processing performedby the medical-image processing apparatus according to the secondembodiment;

FIG. 10 is a diagram illustrating one example of configuration of amedical-image processing apparatus according to a third embodiment;

FIG. 11 includes diagrams illustrating one example of a fusion imagedisplayed on a display unit according to the third embodiment;

FIG. 12 is a flowchart illustrating the procedure of processingperformed by the medical-image processing apparatus according to thethird embodiment;

FIG. 13 is a diagram illustrating one example of a fusion imagedisplayed on a display unit according to a fourth embodiment;

FIG. 14A is a diagram illustrating one example of a fusion imagedisplayed on the display unit according to the fourth embodiment;

FIG. 14B is a diagram illustrating one example of a fusion imagedisplayed on the display unit according to the fourth embodiment;

FIG. 15 is a diagram illustrating one example of a fusion imagedisplayed on the display unit according to the fourth embodiment; and

FIG. 16 is a diagram illustrating one example of a fusion imagedisplayed on the display unit according to the fourth embodiment.

DETAILED DESCRIPTION

According to embodiment, a medical-image processing apparatus comprisingan acquisition unit, a generation unit, an identification unit and adisplay control unit. The acquisition unit that acquires a medical imagecontaining a blood vessel collected by a medical-image diagnosticapparatus. The generation unit that generates an anatomical structuremodel based on the medical image acquired by the acquisition unit. Theidentification unit that identifies a position, on the medical image, ofan index relating to blood flow that is analyzed through fluid analysisusing the anatomical structure model. The display control unit thatdisplays the position of the index on the medical image, and alsodisplay the index associated with the position of the index on themedical image.

A medical-image processing apparatus and a medical-image diagnosticapparatus according to embodiments will now be described with referenceto the drawings. In the embodiments below, embodiments of thismedical-image processing apparatus 100 will be described.

FIG. 1 is a diagram for explaining a configuration example of a system 1including the medical-image processing apparatus 100 according to afirst embodiment. As depicted in FIG. 1, the medical-image processingapparatus 100 according to the first embodiment is connected with amedical-image diagnostic apparatus 200 and an image storage device 300via a network 2 such as an in-house local area network (LAN) installedin a hospital, for example. The respective apparatus and device hereincan directly or indirectly communicate with each other. For example,when a picture archiving and communication system (PACS) is integratedin the system 1, the respective apparatus and device transmit andreceive medical images, for example, between each other according to theDigital Imaging and Communications in Medicine (DICOM) standard.

The medical-image diagnostic apparatus 200 is an X-ray diagnosticapparatus, an X-ray computed tomography (CT) apparatus, a magneticresonance imaging (MRI) apparatus, an ultrasonic diagnostic apparatus, asingle photon emission computed tomography (SPECT) apparatus, a positronemission computed tomography (PET) apparatus, a SPECT-CT apparatus inwhich the SPECT apparatus and the X-ray CT apparatus are integrated, aPET-CT apparatus in which the PET apparatus and the X-ray CT apparatusare integrated, or a group of these apparatus, for example. Themedical-image diagnostic apparatus 200 according to the first embodimentcan generate three-dimensional medical-image data (volume data).

Specifically, the medical-image diagnostic apparatus 200 according tothe first embodiment generates volume data by imaging a subject. Forexample, the medical-image diagnostic apparatus 200 collects data suchas projection data and an MR signal by imaging a subject, andreconstructs medical-image data in a plurality of axial planes along thebody axis of the subject from the collected data, thereby generatingvolume data. For example, the medical-image diagnostic apparatus 200reconstructs medical-image data in 500 axial planes. This group ofmedical-image data in 500 axial planes constitutes the volume data. Theprojection data and the MR signal, for example, themselves of thesubject imaged by the medical-image diagnostic apparatus 200 may be usedas the volume data.

The medical-image diagnostic apparatus 200 according to the firstembodiment transmits the generated volume data to the image storagedevice 300. When transmitting the volume data to the image storagedevice 300, the medical-image diagnostic apparatus 200 transmits assupplementary information, for example, a patient ID for identifying asubject, a test ID for identifying a test, an apparatus ID foridentifying the medical-image diagnostic apparatus 200, a series ID foridentifying one shot of imaging by the medical-image diagnosticapparatus 200.

The image storage device 300 is a database for storing medical images.Specifically, the image storage device 300 according to the firstembodiment stores the volume data transmitted from the medical-imagediagnostic apparatus 200 in a storage unit to store therein the volumedata. In the first embodiment, the volume data stored in the imagestorage device 300 is stored in association with the patient ID, thetest ID, the apparatus ID, and the series ID, for example. Accordingly,the medical-image processing apparatus 100 performs a search using thepatient ID, the test ID, the apparatus ID, and the series ID, forexample, to acquire necessary volume data from the image storage device300.

The medical-image processing apparatus 100 is an image processingapparatus that performs image processing on medical images, and examplesthereof include a workstation, an image server or a viewer of thepicture archiving and communication system (PACS), and various devicesof an electronic health record system. The medical-image processingapparatus 100 according to the first embodiment performs variousprocesses on the volume data acquired from the medical-image diagnosticapparatus 200 or the image storage device 300, performs simulation of aphysiological index for evaluating the presence or absence of myocardialischemia or the degree of the myocardial ischemia, for example, todisplay a simulation result and a medical image. Herein, themedical-image processing apparatus 100 according to the presentembodiment makes it possible to easily compare the simulation result ofthe physiological index based on the fluid analysis with the medicalimage.

As described above, in the conventional techniques, simulation of aphysiological index based on the fluid analysis has been performed, andthe simulation result is displayed on a three-dimensional polygon model.When the three-dimensional polygon model is compared with a medicalimage collected by the medical-image diagnostic apparatus, informationsuch as pixel values and structural information of anatomical tissues ismissing or reduced. Accordingly, only simultaneously displaying thesimulation result and the three-dimensional polygon model is notsufficient for diagnostic performance, and thus comparison with themedical image may be required. For example, in a three-dimensionalpolygon model that is generated by rough modeling, there are occasionswhen stenosis is not recognized on the model and occasions whenconfirmation with the medical image is required. In view of this, themedical-image processing apparatus 100 according to the presentembodiment makes it possible to easily compare the result based on thefluid analysis with the medical image by the configuration described indetail hereinafter.

Specifically, the medical-image processing apparatus 100 according tothe present embodiment generates an anatomical structure model (e.g.,three-dimensional polygon model) based on a medical image generated bythe medical-image diagnostic apparatus 200, and performs fluid analysisprocessing on the generated anatomical structure model to acquire asimulation result of a physiological index (e.g., FFR or CFR). Themedical-image processing apparatus 100 then aligns the acquiredsimulation result with the medical image to display a fusion imageindicating the simulation result at the corresponding position in themedical image thus aligned.

FIG. 2 is a diagram illustrating one example of configuration of themedical-image processing apparatus 100 according to the firstembodiment. A medical-image input unit 110 acquires volume data of amedical image from the medical-image diagnostic apparatus 200 or theimage storage device 300. Specifically, the medical-image input unit 110acquires an image containing blood vessels collected by themedical-image diagnostic apparatus 200. The image containing bloodvessels herein is an image of blood vessels such as coronary arteriesthat are imaged as targets, and includes a medical image collected incontrast imaging and a medical image collected in non-contrast imaging.

For example, the medical-image input unit 110 receives operationperformed by an operator, and acquires volume data of a CT image in acardiac region containing coronary arteries collected by an X-ray CTapparatus as the medical-image diagnostic apparatus 200. Themedical-image input unit 110 then stores the acquired volume data in amedical-image storage unit 131. Herein, the medical-image input unit 110can not only acquire the volume data of a medical image via the network2 but also acquire the volume data via a portable storage medium.

The medical-image storage unit 131 stores therein the medical imageacquired by the medical-image input unit 110. For example, themedical-image storage unit 131 stores therein the volume data of a CTimage in a cardiac region containing coronary arteries acquired by themedical-image input unit 110.

A cardiac-region extraction unit 141 reads volume data of a medicalimage from the medical-image storage unit 131, and extracts the cardiacregion from the volume data thus read. Herein, extraction of the cardiacregion by the cardiac-region extraction unit 141 can be performed byexisting known techniques. For example, the cardiac-region extractionunit 141 uses pattern matching using a human body atlas or a regionexpansion method based on pixel values (voxel values) of the volumedata, for examples, to extract positions of voxels corresponding to thecardiac region in the volume data.

A coronary-region extraction unit 142 then extracts a coronary regioncontained in the cardiac region extracted by the cardiac-regionextraction unit 141. Herein, extraction of the coronary region by thecoronary-region extraction unit 142 can also be performed by existingknown techniques. For example, the coronary-region extraction unit 142uses the region expansion method, for example, to extract positions ofvoxels corresponding to the coronary region from the voxelscorresponding to the cardiac region. In one example, the coronary-regionextraction unit 142 extracts positions of voxels corresponding to thecoronary region on the basis of CT values of voxels that vary dependingon contrast agents in the CT image for the cardiac region.

The coronary-region extraction unit 142 then stores image data of thecoronary region thus extracted in a coronary-region storage unit 132.The coronary-region extraction unit 142 also stores information on theposition of the coronary region extracted in the medical image in amedical-image coronary-region relative-position storage unit 133. Inother words, based on the information on the positions of the voxelscorresponding to the cardiac region in the medical image extracted bythe cardiac-region extraction unit 141, the coronary-region extractionunit 142 extracts positions of voxels, in the volume data of the medicalimage, that correspond to the coronary region extracted from the cardiacregion, and stores information on the extracted positions in themedical-image coronary-region relative-position storage unit 133.

The coronary-region storage unit 132 stores therein image data of thecoronary region extracted by the coronary-region extraction unit 142.The medical-image coronary-region relative-position storage unit 133stores therein information on the positions of voxels, in the volumedata of the medical image, that correspond to the coronary regionextracted by the coronary-region extraction unit 142.

A 3D-coronary-model generation unit 143 generates a 3D coronary model inwhich a coronary artery is three-dimensionally modeled by using theinformation on the voxels corresponding to the coronary region extractedby the coronary-region extraction unit 142. For example, the3D-coronary-model generation unit 143 generates a 3D coronary model thatis a three-dimensional polygon model in which surfaces of the coronaryregion are represented by a group of polygons. FIG. 3 includes diagramsillustrating one example of generation of the 3D coronary model by the3D-coronary-model generation unit 143 according to the first embodiment.For example, the 3D-coronary-model generation unit 143 uses the data ofthe coronary region extracted from the volume data of the CT images togenerate a 3D coronary model as depicted in FIG. 3.

The 3D-coronary-model generation unit 143 sends the generated 3Dcoronary model to a fluid analysis unit 144 described later. The3D-coronary-model generation unit 143 herein stores positional relationbetween the generated 3D coronary model and the medical image in amedical-image 3D-coronary-model relative-position storage unit 134. Forexample, the 3D-coronary-model generation unit 143 stores information onpositions (e.g., coordinates) of voxels corresponding to the respectivepolygons representing the 3D coronary model in the medical-image3D-coronary-model relative-position storage unit 134. The medical-image3D-coronary-model relative-position storage unit 134 stores thereinpositional relation (e.g., coordinate transform matrix) between the 3Dcoronary model generated by the 3D-coronary-model generation unit 143and the medical image.

Referring back to FIG. 2, the fluid analysis unit 144 analyzes indicesrelating to blood flow in blood vessels using the image containing bloodvessels collected by the medical-image diagnostic apparatus 200 on thebasis of fluid analysis. Specifically, the fluid analysis unit 144performs fluid analysis on the 3D coronary model generated by the3D-coronary-model generation unit 143, using various conditions inputfrom a fluid-analysis-initial-condition boundary-condition input unit111, to analyze pressure distribution, blood velocity distribution, andan FFR value, for example, in a coronary vessel. Herein, thefluid-analysis-initial-condition boundary-condition input unit 111receives input of conditions (e.g., mass, viscosity, and flow rate ofblood, Young's modulus of blood vessel) for simulating an index relatingto blood flow in a blood vessel on the basis of fluid analysis. Forexample, the fluid-analysis-initial-condition boundary-condition inputunit 111 receives direct input from an operator. Thefluid-analysis-initial-condition boundary-condition input unit 111herein may acquire the conditions from the database.

FIG. 4 includes diagrams for explaining one example of analysisperformed by the fluid analysis unit 144 according to the firstembodiment. For example, as depicted in FIG. 4, the fluid analysis unit144 performs fluid analysis using the various conditions input by thefluid-analysis-initial-condition boundary-condition input unit 111 onthe 3D coronary model generated by the 3D-coronary-model generation unit143, thereby analyzing the pressure distribution (Pressure (mmHg)) inthe 3D coronary model depicted in the central-upper diagram in FIG. 4and analyzing the blood velocity distribution (Velocity (cm/s)) in the3D coronary model depicted in the central-lower diagram in FIG. 4.

Furthermore, as depicted in the right diagram in FIG. 4, the fluidanalysis unit 144 calculates an FFR value (CT-FFR), for example, in the3D coronary model from the pressure distribution (Pressure (mmHG)) andthe blood velocity distribution (Velocity (cm/s)), for example, in theanalyzed 3D coronary model. For example, as depicted in FIG. 4, thefluid analysis unit 144 analyzes an FFR value in each position of the 3Dcoronary model. The fluid analysis unit 144 then stores a fluid analysisresult such as the pressure distribution, the blood velocitydistribution, and the FFR value in the 3D coronary model in afluid-analysis-result storage unit 135. The fluid analysis unit 144 alsostores positional relation between the 3D coronary model and the fluidanalysis result in a 3D-coronary-model fluid-analysis-resultrelative-position storage unit 136.

The fluid-analysis-result storage unit 135 stores therein the fluidanalysis result obtained by the fluid analysis unit 144. The3D-coronary-model fluid-analysis-result relative-position storage unit136 stores therein the positional relation between the fluid analysisresult obtained by the fluid analysis unit 144 and the 3D coronarymodel.

An alignment processing unit 145 identifies the position, on the image,of the index relating to blood flow in a blood vessel analyzed throughthe fluid analysis using the image containing blood vessels collected bythe medical-image diagnostic apparatus 200. Specifically, the alignmentprocessing unit 145 identifies the position, on the image, of the indexanalyzed through the fluid analysis using the 3D polygon model extractedfrom the image containing blood vessels. For example, the alignmentprocessing unit 145 identifies the position, on the CT image, of theresult of fluid analysis using the 3D coronary model generated by usingthe coronary arteries extracted from the CT image.

In one example, the alignment processing unit 145 first readsinformation on positions of voxels corresponding to the coronary regionin volume data of a medical image stored by the medical-imagecoronary-region relative-position storage unit 133 and information onthe position of the 3D coronary model in the volume data of the medicalimage stored by the medical-image 3D-coronary-model relative-positionstorage unit 134 to identify the position of the 3D coronary modelcorresponding to the position of the coronary region in the medicalimage, thereby aligning the coronary region with the 3D coronary model.

The alignment processing unit 145 then reads the position of the fluidanalysis result in the 3D coronary model stored by the 3D-coronary-modelfluid-analysis-result relative-position storage unit 136, and associatesthis position with the coronary region with which the fluid analysisresult is aligned. In other words, the alignment processing unit 145identifies the position of the fluid analysis result in the coronaryregion. The alignment processing unit 145 then sends information on theidentified position to a medical-image fluid-analysis-resultfusion-image generation unit 146 described later.

As described above, the alignment processing unit 145 aligns a medicalimage with an anatomical structure model, so that, for example, themedical-image fluid-analysis-result fusion-image generation unit 146 cangenerate a fusion image in which a simulation result is indicated at anaccurate position of a blood vessel contained in the medical image.Herein, a method of alignment is not limited to the above-describedmethod, and any other methods may be used therefor. For example,alignment may be performed with reference to an anatomical landmark ofthe medical image and the anatomical structure model. In this case, forexample, the alignment processing unit 145 aligns a coronary arterycontained in volume data of the medical image with the 3D coronary modelwith reference to the anatomical landmark. The alignment processing unit145 then associates the position of the fluid analysis result in the 3Dcoronary model with the coronary artery contained in the volume data toidentify the position of the fluid analysis result in the coronaryregion.

The medical-image fluid-analysis-result fusion-image generation unit 146displays the position on the image containing blood vessels and alsodisplays the index associated with the position on a display unit 120.Specifically, based on the position of the fluid analysis result in thecoronary region aligned by the alignment processing unit 145, themedical-image fluid-analysis-result fusion-image generation unit 146generates a fusion image in which the fluid analysis result is indicatedin the corresponding position of the medical image read from themedical-image storage unit 131, and displays the generated fusion imageon the display unit 120.

FIG. 5 includes diagrams illustrating one example of fusion imagesdisplayed on the display unit 120 according to the first embodiment. Forexample, the medical-image fluid-analysis-result fusion-image generationunit 146 generates a fusion image in which the fluid analysis results“CT-FFR: 0.90” and “CT-FFR: 0.67” obtained by the fluid analysis unit144 are associated with positions corresponding to coronary arteries ina CT image of a heart as depicted in the left diagram of FIG. 5, anddisplays the fusion image on the display unit 120. This operationenables an observer to perform diagnosis while comparing the fluidanalysis results with morphological information, so that diagnosticperformance can be improved.

Herein, the medical-image fluid-analysis-result fusion-image generationunit 146 can generate not only a volume rendering image but also afusion image in which the fluid analysis results “CT-FFR: 0.90” and“CT-FFR: 0.67” are associated with positions corresponding to coronaryarteries in a curved multi planer reconstruction (CPR) image or an MPRimage as depicted in the right-upper row of FIG. 5, for example, anddisplay the fusion images on the display unit 120. The medical-imagefluid-analysis-result fusion-image generation unit 146 can also generatea fusion image in which a fluid analysis result such as pressuredistribution is indicated in a cross section (CS) image of coronaryarteries as depicted in the right-lower row of FIG. 5, for example, anddisplay the fusion image on the display unit 120. In this manner, themedical-image fluid-analysis-result fusion-image generation unit 146 cangenerate various images from the original volume data, and can generateand display fusion images in which the fluid analysis results aredisplayed on the generated images. Herein, the fluid analysis results tobe indicated on a medical image can be optionally selected and, forexample, it is possible to indicate difference of pressure distributionin coronary arteries in different colors, and generate and display afusion image in which FFR values are indicated in the respectivepositions of the coronary arteries.

FIG. 6 is a flowchart illustrating the procedure of processing performedby the medical-image processing apparatus 100 according to the firstembodiment. In FIG. 6, a case is illustrated in which a fluid analysisresult based on a 3D coronary model generated from a medical image isindicated on a CT image. As depicted in FIG. 6, in the medical-imageprocessing apparatus 100 according to the first embodiment, themedical-image input unit 110 acquires a medical image (step S101), andthe cardiac-region extraction unit 141 and the coronary-regionextraction unit 142 extract a cardiac region in the medical image and acoronary region in the cardiac region, respectively. The coronary-regionextraction unit 142 then causes the medical-image coronary-regionrelative-position storage unit 133 to store therein positions ofcoronary arteries in the medical image (step S102).

Subsequently, the 3D-coronary-model generation unit 143 generates a 3Dcoronary model using the extracted coronary region, and causes themedical-image 3D-coronary-model relative-position storage unit 134 tostore therein the relative position of the 3D coronary model in themedical image (step S103). Furthermore, the fluid analysis unit 144performs fluid analysis processing on the generated 3D coronary model,and causes the 3D-coronary-model fluid-analysis-result relative-positionstorage unit 136 to store therein the position of the analysis result inthe 3D coronary model (step S104).

The alignment processing unit 145 then identifies the position of theanalysis result in the medical image on the basis of the positions ofthe coronary arteries in the medical image stored in the medical-imagecoronary-region relative-position storage unit 133, the relativeposition of the 3D coronary model in the medical image stored in themedical-image 3D-coronary-model relative-position storage unit 134, andthe position of the analysis result in the 3D coronary model stored inthe 3D-coronary-model fluid-analysis-result relative-position storageunit 136 to align the position of the analysis result on the medicalimage (step S105).

Subsequently, the medical-image fluid-analysis-result fusion-imagegeneration unit 146 generates a fusion image in which the position ofthe analysis result and the analysis result are displayed on the medicalimage (step S106), and displays the generated fusion image on thedisplay unit 120 (step S107).

As described above, according to the first embodiment, the alignmentprocessing unit 145 identifies the position, on the image, of the indexrelating to blood flow in a blood vessel analyzed through fluid analysisusing the image containing the blood vessels collected by themedical-image diagnostic apparatus 200. The medical-imagefluid-analysis-result fusion-image generation unit 146 displays theposition on the image containing the blood vessels and also displays theindex associated with the position on the display unit 120. Thus, themedical-image processing apparatus 100 according to the first embodimentcan display the analysis result based on the fluid analysis at anaccurate position in the medical image, and makes it possible to easilycompare the result based on the fluid analysis with the medical image.

Consequently, a morphological state of blood vessels can be easilychecked, whereby diagnostic performance can be improved. For example, ifan FFR value is small in the analysis result based on the fluidanalysis, the degree of stenosis on this stenosis can be easily checkedvisually.

Furthermore, according to the first embodiment, the alignment processingunit 145 identifies the position, on the image, of the index analyzedthrough fluid analysis using a three-dimensional polygon model extractedfrom the image containing blood vessels. Thus, the medical-imageprocessing apparatus 100 according to the first embodiment makes itpossible to easily identify the position by using existing techniques.

In a second embodiment, a case will be described in which a fusion imagein which a fluid analysis result is indicated on an analysis imageobtained by analyzing a medical image is generated and displayed. FIG. 7is a diagram illustrating one example of configuration of amedical-image processing apparatus 100 a according to the secondembodiment. In the second embodiment, a case of using a perfusion imageas the analysis image will be described. As depicted in FIG. 7, themedical-image processing apparatus 100 a according to the secondembodiment is different from the medical-image processing apparatus 100according to the first embodiment depicted in FIG. 2 in additionallyhaving a myocardial-perfusion-analysis processing unit 147, amedical-image perfusion-analysis-result relative-position storage unit137, and a perfusion-analysis-result storage unit 138 and also inprocessing performed by the alignment processing unit 145 and themedical-image fluid-analysis-result fusion-image generation unit 146.The following describes these differences focusing thereon.

The myocardial-perfusion-analysis processing unit 147 performsmyocardial perfusion analysis using a medical image stored by themedical-image storage unit 131. Specifically, themyocardial-perfusion-analysis processing unit 147 calculates temporalconcentration changes of a CT value based on CT images obtained byimaging on a time-series basis a cardiac region of a subject to whom acontrast agent is administered. The myocardial-perfusion-analysisprocessing unit 147 then generates a perfusion image in which an indexrepresenting a dynamic behavior of blood flow passing through acapillary in a tissue is mapped on the tissue from the calculatedtemporal concentration changes of the CT value.

The myocardial-perfusion-analysis processing unit 147 then storesinformation on each position of the perfusion analysis result (indexrepresenting dynamic behavior of blood flow passing through thecapillary) in the medical image in the medical-imageperfusion-analysis-result relative-position storage unit 137. Themyocardial-perfusion-analysis processing unit 147 also stores thegenerated perfusion image in the perfusion-analysis-result storage unit138.

The medical-image perfusion-analysis-result relative-position storageunit 137 stores therein the information on each position of theperfusion analysis result in volume data of the medical image. Theperfusion-analysis-result storage unit 138 stores therein the perfusionimage.

The alignment processing unit 145 according to the second embodimentidentifies the position of the index on an analysis image generatedbased on the medical image. Specifically, the alignment processing unit145 identifies the position, on the analysis image, of the indexanalyzed through fluid analysis using a 3D polygon model. For example,the alignment processing unit 145 identifies the position, on theperfusion image, of the result of fluid analysis using a 3D coronarymodel generated by using coronary arteries extracted from a CT image.

In one example, the alignment processing unit 145 first readsinformation on each position of the perfusion analysis result in volumedata of a medical image stored by the medical-imageperfusion-analysis-result relative-position storage unit 137,information on the positions of voxels corresponding to the coronaryregion in the volume data of the medical image, and information on theposition of the 3D coronary model in the volume data of the medicalimage to identify relative positions between the respective pieces ofinformation, thereby aligning the perfusion analysis result with thecoronary region and with the 3D coronary model in the medical image.

The alignment processing unit 145 then identifies the position of thefluid analysis result in the coronary region for which the perfusionanalysis result is aligned with the coronary region and with the 3Dcoronary model in the medical image. The alignment processing unit 145then sends information on the identified position to the medical-imagefluid-analysis-result fusion-image generation unit 146.

The medical-image fluid-analysis-result fusion-image generation unit 146according to the second embodiment displays the position on the analysisimage and also displays the index associated with the position on thedisplay unit 120. Specifically, based on the perfusion analysis result,the coronary region, and the 3D coronary model that are aligned in themedical image by the alignment processing unit 145, and based on theposition of the fluid analysis result in the coronary region, themedical-image fluid-analysis-result fusion-image generation unit 146generates a fusion image in which the fluid analysis result is indicatedin the corresponding position of the perfusion image read from theperfusion-analysis-result storage unit 138, and displays the generatedfusion image on the display unit 120.

FIG. 8 is a diagram illustrating one example of the fusion imagedisplayed on the display unit 120 according to the second embodiment.For example, the medical-image fluid-analysis-result fusion-imagegeneration unit 146 generates a fusion image in which the fluid analysisresults “CT-FFR: 0.90” and “CT-FFR: 0.67” obtained by the fluid analysisunit 144 are associated with positions corresponding to coronaryarteries in a perfusion image of a cardiac region as depicted in FIG. 8,and displays the fusion image on the display unit 120.

FIG. 9 is a flowchart illustrating the procedure of processing performedby the medical-image processing apparatus 100 a according to the secondembodiment. In FIG. 9 the same step numbers are given to the sameprocesses as those of the flowchart depicted in FIG. 6, and thus adetail description thereof is omitted. As depicted in FIG. 9, in themedical-image processing apparatus 100 a according to the secondembodiment, a medical image is acquired (step S101), positions ofcoronary arteries in the medical image are stored (step S102), therelative position of a 3D coronary model in the medical image is stored(step S103), and the position of the analysis result in the 3D coronarymodel is stored (step S104).

Subsequently, the myocardial-perfusion-analysis processing unit 147performs perfusion analysis processing using the medical image, andcauses the medical-image perfusion-analysis-result relative-positionstorage unit 137 to store therein the position of the perfusion analysisresult in the medical image (step S201). The alignment processing unit145 then identifies the positions of the analysis result and theperfusion analysis result in the medical image on the basis of theperfusion analysis results stored in the medical-imageperfusion-analysis-result relative-position storage unit 137, thepositions of the coronary arteries in the medical image stored in themedical-image coronary-region relative-position storage unit 133, therelative position of the 3D coronary model in the medical image storedin the medical-image 3D-coronary-model relative-position storage unit134, and the position of the analysis result in the 3D coronary modelstored in the 3D-coronary-model fluid-analysis-result relative-positionstorage unit 136 to align the positions of the analysis result and theperfusion analysis result on the medical image (step S202).

Subsequently, the medical-image fluid-analysis-result fusion-imagegeneration unit 146 generates a fusion image in which the position ofthe analysis result, the analysis result, and the perfusion analysisresult are displayed on the medical image (step S203), and displays thegenerated fusion image on the display unit 120 (step S204).

As described above, according to the second embodiment, the alignmentprocessing unit 145 identifies the position of the index on theperfusion image generated based on the medical image. The medical-imagefluid-analysis-result fusion-image generation unit 146 displays theposition on the perfusion image, and also displays the index associatedwith the position on the display unit 120. Thus, the medical-imageprocessing apparatus 100 a according to the second embodiment makes itpossible to easily compare the result based on the fluid analysis withthe analysis image based on the medical image. Consequently, diagnosticperformance can be further improved. For example, if ischemia isobserved in a perfusion image, the FFR value of the blood vesselresponsible therefor can be easily checked.

In a third embodiment, a case will be described in which analysisresults based on fluid analysis are indicated on different medicalimages. FIG. 10 is a diagram illustrating one example of configurationof a medical-image processing apparatus 100 b according to the thirdembodiment. In the third embodiment, a case of indicating an analysisresult obtained by fluid analysis using a 3D coronary model generatedfrom a CT image on an MR image will be described as an example. Asdepicted in FIG. 10, the medical-image processing apparatus 100 baccording to the third embodiment is different from the medical-imageprocessing apparatus 100 according to the first embodiment depicted inFIG. 2 in additionally having an inter-medical-image alignmentprocessing unit 148 and an inter-medical-image relative-position storageunit 139 and also in processing performed by the alignment processingunit 145 and the medical-image fluid-analysis-result fusion-imagegeneration unit 146. The following describes these differences focusingthereon.

The inter-medical-image alignment processing unit 148 performs alignmentbetween different medical images stored by the medical-image storageunit 131. For example, the inter-medical-image alignment processing unit148 performs alignment between a CT image and an MR image in both ofwhich a cardiac region of the same subject is imaged. Herein, theprocessing of the alignment between the medical images by theinter-medical-image alignment processing unit 148 can be performed byexisting known techniques and, for example, by examining similarity ofvoxels between two medical images, alignment of the image is performed.The inter-medical-image relative-position storage unit 139 storestherein information on alignment between different medical imagesperformed by the inter-medical-image alignment processing unit 148.

The alignment processing unit 145 according to the third embodimentperforms alignment between medical images containing blood vesselscollected by different types of medical-image diagnostic apparatus toidentify positions of indices on the different types of images.Specifically, the alignment processing unit 145 identifies positions, ondifferent medical images, of indices analyzed through fluid analysisusing a 3D polygon model. For example, the alignment processing unit 145identifies the position, on an MR image, of the fluid analysis resultobtained by using a 3D coronary model generated by using coronaryarteries extracted from a CT image.

In one example, the alignment processing unit 145 first readsinformation on alignment between a CT image and an MR image stored bythe inter-medical-image relative-position storage unit 139, informationon positions of voxels corresponding to a coronary region in volume dataof the CT image, and information on the position of a 3D coronary modelin the volume data of the CT image to identify relative positions of therespective pieces of information, thereby performing alignment betweenthe coronary region in the MR image and the 3D coronary model.

The alignment processing unit 145 then identifies the position of thefluid analysis result in the coronary region for which alignment betweenthe coronary region in the MR image and the 3D coronary model isperformed. The alignment processing unit 145 then sends information onthe identified position to the medical-image fluid-analysis-resultfusion-image generation unit 146.

The medical-image fluid-analysis-result fusion-image generation unit 146according to the third embodiment displays the position on differenttypes of images and also displays the index associated with the positionon the display unit 120. Specifically, based on the coronary region inthe MR image and the 3D coronary model that are aligned by the alignmentprocessing unit 145, and also based on the position of the fluidanalysis result in the coronary region, the medical-imagefluid-analysis-result fusion-image generation unit 146 generates afusion image in which the fluid analysis result is indicated at thecorresponding position on the MR image read from the medical-imagestorage unit 131, and displays the generated fusion image on the displayunit 120.

FIG. 11 includes diagrams illustrating one example of the fusion imagedisplayed on the display unit 120 according to the third embodiment. Forexample, as depicted in FIG. 11, the medical-image fluid-analysis-resultfusion-image generation unit 146 generates a fusion image in which thefluid analysis result “CT-FFR: 0.71” of a 3D coronary model generatedfrom a CT image at a corresponding position on the MR image aligned withthe CT image, and displays the fusion image on the display unit 120.This operation makes it possible to compare medical images that arecollected by different modalities with the fluid analysis result, andthus diagnostic performance can be improved. The above-described exampleis merely an example and the medical images to be used are not limitedto the above-described ones, and any types of medical images can beused.

In the above-described examples, a case of displaying a fusion image hasbeen described in which a fluid analysis result is indicated on anoriginal image of an MR image, but the medical-image processingapparatus 100 b according to the present embodiment can generate anddisplay a fusion image in which the fluid analysis result is indicatedon an analysis image of the MR image. For example, the medical-imageprocessing apparatus 100 b depicted in FIG. 10 further includes themyocardial-perfusion-analysis processing unit 147, the medical-imageperfusion-analysis-result relative-position storage unit 137, and theperfusion-analysis-result storage unit 138 depicted in FIG. 7. Thealignment processing unit 145 performs alignment with the analysisimage, and the medical-image fluid-analysis-result fusion-imagegeneration unit 146 generates a fusion image in which the fluid analysisresult is indicated on the analysis image to display the fusion image onthe display unit 120.

FIG. 12 is a flowchart illustrating the procedure of processingperformed by the medical-image processing apparatus 100 b according tothe third embodiment. In FIG. 12, a case is illustrated in which fluidanalysis results based on a 3D coronary model generated from a CT imageis indicated on an MR image. As depicted in FIG. 12, in themedical-image processing apparatus 100 b according to the thirdembodiment, the medical-image input unit 110 acquires a CT image and anMR image (step S301), the inter-medical-image alignment processing unit148 aligns the CT image with the MR image and stores the relativeposition in the inter-medical-image relative-position storage unit 139(step S302).

The cardiac-region extraction unit 141 and the coronary-regionextraction unit 142 then extract a cardiac region in the CT image and acoronary region in the cardiac region, respectively. The coronary-regionextraction unit 142 then stores positions of coronary arteries in the CTimage in the medical-image coronary-region relative-position storageunit 133 (step S303).

Subsequently, the 3D-coronary-model generation unit 143 generates a 3Dcoronary model using the extracted coronary region, and stores therelative position of the 3D coronary model in the CT image in themedical-image 3D-coronary-model relative-position storage unit 134 (stepS304). Furthermore, the fluid analysis unit 144 performs fluid analysisprocessing on the generated 3D coronary model, and stores the positionof the analysis result in the 3D coronary model in the 3D-coronary-modelfluid-analysis-result relative-position storage unit 136 (step S305).

The alignment processing unit 145 then identifies the position of theanalysis result in the CT image on the basis of the positions ofcoronary arteries in the CT image, the relative position of the 3Dcoronary model in the CT image, and the position of the analysis resultin the 3D coronary model (step S306). Furthermore, the alignmentprocessing unit 145 identifies the position of the analysis result inthe MR image on the basis of information on the alignment between the CTimage and the MR image and the position of the analysis result in the MRimage (step S307).

Subsequently, the medical-image fluid-analysis-result fusion-imagegeneration unit 146 generates a fusion image in which the position ofthe analysis result and the analysis result are displayed on the MRimage (step S308), and displays the generated fusion image on thedisplay unit 120 (step S309).

As described above, according to the third embodiment, the alignmentprocessing unit 145 performs alignment between different types ofmedical images collected by different types of medical-image diagnosticapparatus, thereby identifying the position of an index on the differentmedical images. The medical-image fluid-analysis-result fusion-imagegeneration unit 146 displays the position on the different medicalimages and also displays the index associated with the position on thedisplay unit 120. Thus, the medical-image processing apparatus 100 baccording to the third embodiment can display the fluid analysis resulton various medical images, and enables diagnostic performance to befurther improved.

Embodiments are not limited to the above-described embodiments, and canbe implemented in other various forms.

In the above-described embodiments, cases have been described in which afluid analysis result is displayed on a medical image or an analysisimage. However, the embodiments are not limited to these cases, and maybe cases of displaying information that is indicated in combination withan analysis result obtained by analyzing a medical image and a fluidanalysis result. Specifically, the medical-image fluid-analysis-resultfusion-image generation unit 146 according to the fourth embodimentdisplays evaluation information that is derived from an analysis resultobtained by analyzing an index relating to blood flow and an analysisimage, in association with the position of the index on the analysisimage. For example, it is possible to combine myocardial abnormalityevaluated by myocardial perfusion with a CT-FFR value, define thestenosis treatment level according to these states, and display thelevel on the analysis image.

In one example, the stenosis treatment level is defined based on themyocardial abnormality in a blood-vessel dominant region and the CT-FFRvalue. The stenosis treatment level herein can be optionally set, andcan be set as, for example, “Level 1: myocardial abnormality &FFR<0.75”, “Level 2: myocardial abnormality & FFR≥0.75”, “Level 3:myocardial normality & FFR<0.75”, and “Level 4: myocardial normality &FFR≥0.75”. The medical-image fluid-analysis-result fusion-imagegeneration unit 146 reads a perfusion analysis result from themedical-image perfusion-analysis-result relative-position storage unit137, extracts an index representing hemodynamics in the dominant regionfor each position of blood vessels, and associates the index with theCT-FFR value.

The medical-image fluid-analysis-result fusion-image generation unit 146then refers to the above-described stenosis treatment level, generates afusion image in which corresponding levels are indicated for therespective positions of the blood vessels, and displays the generatedfusion image on the display unit 120. FIG. 13 is a diagram illustratingone example of the fusion image displayed on the display unit 120according to the fourth embodiment. For example, as depicted in FIG. 13,the medical-image fluid-analysis-result fusion-image generation unit 146generates a fusion image in which the stenosis treatment levels “Level 1CT-FFR: 0.67” and “Level 4 CT-FFR: 0.90” are associated with thecorresponding positions of the coronary arteries in the perfusion imageof the cardiac region, and displays the fusion image on the display unit120.

Herein, the medical-image fluid-analysis-result fusion-image generationunit 146 may indicate the stenosis treatment levels by indicatingnumbers for the levels in the image as depicted in FIG. 13 or,alternatively, may display the levels in different colors. For example,the medical-image fluid-analysis-result fusion-image generation unit 146displays Level 1 emphatically in red, and displays Level 4 in blue. Thisoperation enables an operator to observe a plurality of analysis resultsusing medical images as an integrated evaluation result.

Display by the medical-image processing apparatus 100 is not limited tothe above-described examples, and display can be performed in variousother manners. For example, the medical-image fluid-analysis-resultfusion-image generation unit 146 can perform display in various mannersfor each stenosis. FIGS. 14A and 14B are diagrams each illustrating oneexample of a fusion image displayed on a display unit according to thefourth embodiment. For example, as depicted in FIG. 14A, themedical-image fluid-analysis-result fusion-image generation unit 146 candisplay each of “Stenosis 1: CT-FFR: 0.4”, “Stenosis 2: CT-FFR: 0.6”,and “Stenosis 3: CT-FFR: 0.9” for each stenosis in a switched manner. InFIG. 14A, all stenoses are illustrated but, actually, each stenosis isdisplayed one by one.

In this case, for example, the medical-image fluid-analysis-resultfusion-image generation unit 146 makes a list of stenotic portions inthe ascending order of CT-FFR values, and displays them one by one inthe order of the list in response to operation of an operator. Thisoperation allows the operator to observe the peripheries of the stenosesin the ascending order of CT-FFR values and check the status. The listof stenotic portions can be made in any order, and may be made in thedescending order. Making of the list of stenotic portions may beperformed for all stenoses, but the making may be performed only forstenoses the CT-FFR values of which are smaller than or equal to acutoff value for CT-FFR values after setting the cutoff value inadvance.

Furthermore, for example, the medical-image fluid-analysis-resultfusion-image generation unit 146 can generate a CPR image and a CS imagefrom volume data for the stenosis 1 to display the generated imagesassociated with each other as depicted in FIG. 14B, thereby performing amore detailed check, which can be used also for a prior check when astent is placed.

Furthermore, in the above-described third embodiment, a case has beendescribed in which a CT image and an MR image that are obtained byimaging a cardiac region of the same subject are used and a fluidanalysis result based on a three-dimensional polygon model generatedfrom the CT image is combined with the MR image, but the embodiments arenot limited to this case, and various other medical images can be usedtherefor.

FIG. 15 is a diagram illustrating one example of a fusion imagedisplayed on the display unit according to the fourth embodiment. Forexample, as depicted in FIG. 15, the medical-image fluid-analysis-resultfusion-image generation unit 146 can also superimpose athree-dimensional image of coronary arteries generated from volume dataof a CT image and a three-dimensional analysis image based onthree-dimensional data of a heart collected by an ultrasonic diagnosticapparatus on one another, and can display a fusion image in which aCT-FFR value is indicated on a coronary artery on the display unit 120.In this case, the alignment processing unit 145 aligns the volume dataof the CT image with the volume data of the ultrasonic image. Based onthis alignment information, the medical-image fluid-analysis-resultfusion-image generation unit 146 then displays a fusion image in whichthe three-dimensional image of the coronary arteries, the threedimensional analysis image of the heart, and the fluid analysis resultare combined.

Furthermore, performing the above-described alignment also enablescombination with other analysis images. FIG. 16 is a diagramillustrating one example of a fusion image displayed on the display unitaccording to the fourth embodiment. For example, as depicted in FIG. 16,the medical-image fluid-analysis-result fusion-image generation unit 146can display, on the display unit 120, a fusion image in which a CT-FFRvalue is indicated at a blood vessel on a polar-map generated based onultrasonic data. The polar-map herein is image data obtained by planarlyexpanding three-dimensional data in which three-dimensionalcardiac-function information is mapped, and FIG. 16 is an image in whichblood-vessel images indicating blood vessels are projected onto thepolar-map.

In this manner, the medical-image processing apparatus 100 according tothe present application displays a fusion image in which a fluidanalysis result is indicated on a medical image, thereby making itpossible to easily compare the fluid analysis result with the medicalimage. Herein, examples of the image on which the fluid analysis resultis combined include a medical image used for generating an anatomicalstructure model used in the fluid analysis, an analysis image obtainedby analyzing the medical image used for generating the anatomicalstructure model, a different type of medical image collected by amodality different from that for the medical image used for generatingthe anatomical structure model, or an analysis image obtained byanalyzing the different type of medical image. Furthermore, the image onwhich the fluid analysis result is combined may be a single image out ofthe above-described images, or may be an image on which the medicalimage and the analysis image are combined.

In the above-described embodiments, cases have been described in whichfluid analysis is performed by using a three-dimensional polygon modelgenerated from a medical image. However, the embodiments are not limitedto these cases, and may be cases in which the fluid analysis isperformed by using volume data of the medical image. In this case, forexample, the medical-image processing apparatus 100 extracts voxelscorresponding to an inner wall of a coronary artery from the volume dataof the medical image, and performs fluid analysis by using a group ofthe extracted voxels.

In the above-described embodiments, cases have been described in whichthe medical-image processing apparatus perform various processes.However, the embodiments are not limited to these cases, and may be usedfor medical-image diagnostic apparatus such as an ultrasonic diagnosticapparatus, a magnetic resonance imaging apparatus, and anuclear-medicine imaging apparatus.

In the above-described embodiments, FFR is used as an example for anindex relating to blood flow, but the embodiments are not limited tothis, and CFR or other indices obtained by customizing these indices maybe used.

In the above-described embodiment, coronary arteries have beenconsidered, but the embodiments are not limited to this, and can be usedfor other blood vessels in the same manner.

The configurations of the medical-image processing apparatus describedin the above-described embodiments are merely examples, and eachconfiguration can be appropriately integrated or divided.

With the medical-image processing apparatus and the medical-imagediagnostic apparatus according to at least one of the above-describedembodiments, comparison between a fluid analysis result and a medicalimage can be easily performed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A medical-image processing apparatus, comprising:processing circuitry configured to acquire a first medical imagecontaining a coronary artery and a second medical image containing amyocardial tissue, extract the coronary artery in the first medicalimage and the myocardial tissue in the second medical image; identify apositional relationship between the first medical image and the secondmedical image based on the extraction results of the coronary artery andthe myocardial tissue, generate a blood flow image representing an indexrelating to blood flow that is analyzed through the coronary artery byfluid analysis on the first medical image, wherein the blood flow imagerepresents the index relating to blood flow on the extracted coronaryartery, generate a perfusion image showing a perfusion indexrepresenting a dynamic behavior of blood flow passing through themyocardial tissue, the perfusion index being obtained by perfusionanalysis on the second medical image, wherein the perfusion imagerepresents the perfusion index on the extracted myocardial tissue,generate a combined image by combining the blood flow image and theperfusion image based on the positional relationship, identify adominant region on the myocardial tissue where a target branch of thecoronary artery feeds blood, determine whether a myocardial abnormalityis included in the dominant region based on the perfusion index, obtainthe index relating to blood flow at the target branch of the coronaryartery, calculate a treatment index indicating necessity of treatmentfor the target branch of the coronary artery using a determinationresult of the myocardial abnormality and the index relating to bloodflow at the target branch of the coronary artery, and cause a display todisplay the treatment index in association with the target branch of thecoronary artery on the combined image.
 2. The medical-image processingapparatus according to claim 1, wherein the first medical image and thesecond medical image are collected respectively by different types ofmedical-image diagnostic apparatuses.
 3. The medical-image processingapparatus according to claim 2, wherein the processing circuitry isfurther configured to analyze the index relating to blood flow in thecoronary artery based on the fluid analysis using the first medicalimage, and analyze the perfusion index in the myocardial tissue based onthe perfusion analysis using the second medical image.
 4. Themedical-image processing apparatus according to claim 1, wherein theprocessing circuitry is further configured to analyze the index relatingto blood flow in the coronary artery based on the fluid analysis usingthe first medical image, and analyze the perfusion index in themyocardial tissue based on the perfusion analysis using the secondmedical image.
 5. The medical-image processing apparatus according toclaim 1, wherein the processing circuitry is further configured toextract information of each voxel position in the second medical imageand store the information of each voxel position in a memory, identify aposition of the index relating to blood flow and a position of theperfusion index in the second medical image based on the information ofeach voxel position, and perform a registration between a surface of themyocardial tissue and the index relating to blood flow based on theposition of the index relating to blood flow and the position of theperfusion index in the second medical image.
 6. The medical-imageprocessing apparatus according to claim 1, wherein the processingcircuitry is further configured to identify a position of the perfusionindex in the second medical image, identify a position corresponding toa coronary artery region in the second medical image, identify aposition of a 3D coronary model in the coronary artery region, the 3Dcoronary model being an anatomical structure model used to calculate theindex relating to blood flow, and perform a registration between theperfusion index and the index relating to blood flow by identifying arelative position of the perfusion index, the coronary artery region andthe 3D coronary model.
 7. The medical-image processing apparatusaccording to claim 1, wherein the processing circuitry is furtherconfigured to perform a registration between the blood flow image andthe perfusion image, and cause the display to display a fusion image inwhich the blood flow image and the perfusion image are superimposedbased on a result of the registration.
 8. An image processing methodperformed by a medical image processing apparatus, the image processingmethod comprising: acquiring a first medical image containing a coronaryartery and a second medical image containing a myocardial tissue;extracting the coronary artery in the first medical image and themyocardial tissue in the second medical image; identifying a positionalrelationship between the first medical image and the second medicalimage based on the extraction results of the coronary artery and themyocardial tissue; generating a blood flow image representing an indexrelating to blood flow that is analyzed through the coronary artery byfluid analysis on the first medical image; wherein the blood flow imagerepresents the index relating to blood flow on the extracted coronaryartery; generating a perfusion image showing a perfusion indexrepresenting a dynamic behavior of blood flow passing through themyocardial tissue, the perfusion index being obtained by perfusionanalysis on the second medical image, wherein the perfusion imagerepresents the perfusion index on the extracted myocardial tissue;generating a combined image by combining the blood flow image and theperfusion image based on the positional relationship; identifying adominant region on the myocardial tissue where a target branch of thecoronary artery feeds blood, determining whether a myocardialabnormality is included in the dominant region based on the perfusionindex, obtaining the index relating to blood flow at the target branchof the coronary artery, calculating a treatment index indicatingnecessity of treatment for the target branch of the coronary arteryusing a determination result of the myocardial abnormality and the indexrelating to blood flow at the target branch of the coronary artery, andcausing a display to display the treatment index in association with thetarget branch of the coronary artery on the combined image.
 9. The imageprocessing method according to claim 8, wherein the image processingmethod further comprising: extracting information of each voxel positionin the second medical image and store the information of each voxelposition in a memory, identifying a position of the index relating toblood flow and a position of the perfusion index in the second medicalimage based on the information of each voxel position, and performing aregistration between a surface of the myocardial tissue and the indexrelating to blood flow based on the position of the index relating toblood flow and the position of the perfusion index in the second medicalimage.
 10. The image processing method according to claim 8, wherein theimage processing method further comprising: identifying a position ofthe perfusion index in the second medical image, identifying a positioncorresponding to a coronary artery region in the second medical image,identifying a position of a 3D coronary model in the coronary arteryregion, the 3D coronary model being an anatomical structure model usedto calculate the index relating to blood flow, and performing aregistration between the perfusion index and the index relating to bloodflow by identifying a relative position of the perfusion index, thecoronary artery region and the 3D coronary model.
 11. The imageprocessing method according to claim 8, wherein the image processingmethod further comprising: performing a registration between the bloodflow image and the perfusion image, and causing the display to display afusion image in which the blood flow image and the perfusion image aresuperimposed based on a result of the registration.
 12. A medical-imageprocessing apparatus, comprising: processing circuitry configured tocause a display to display a combined image by combining a blood flowimage representing indices relating to blood flow on a coronary arteryand a perfusion image representing a perfusion index on myocardialtissue, wherein the indices relating to blood flow are analyzed throughthe coronary artery by fluid analysis on medical image data containingthe coronary artery, the perfusion index represents a dynamic behaviorof blood flow passing through the myocardial tissue and is obtained byperfusion analysis on medical image data containing the myocardialtissue, obtain an index relating to blood flow at a target vessel of thecoronary artery, determine a correspondence between the target vesseland the perfusion index, the perfusion index being related to amyocardial abnormality, calculate a treatment index indicating necessityof treatment for the target vessel of the coronary artery using thedetermined correspondence and the index relating to blood flow at thetarget vessel of the coronary artery, and cause a display to display thetreatment index in association with the target vessel of the coronaryartery.
 13. The medical-image processing apparatus according to claim12, wherein the medical image data containing the coronary artery andthe medical image data containing the myocardial tissue are collectedrespectively by different types of medical-image diagnostic apparatuses.14. The medical-image processing apparatus according to claim 12,wherein the processing circuitry is further configured to analyze theindices relating to blood flow in the coronary artery based on the fluidanalysis using the medical image data containing the coronary artery,and analyze the perfusion index in the myocardial tissue based on theperfusion analysis using the medical image data containing themyocardial tissue.
 15. The medical-image processing apparatus accordingto claim 12, wherein the processing circuitry is further configured toextract information of each voxel position in the medical image data andstore the information of each voxel position in a memory, identify aposition of the index relating to blood flow and a position of theperfusion index in the medical image data based on the information ofeach voxel position, and perform a registration between a surface of themyocardial tissue and the index relating to blood flow based on theposition of the index relating to blood flow and the position of theperfusion index in the medical image data.
 16. The medical-imageprocessing apparatus according to claim 12, wherein the processingcircuitry is further configured to identify a position of the perfusionindex in the medical image data, identify a position corresponding to acoronary artery region in the medical image data, identify a position ofa 3D coronary model in the coronary artery region, the 3D coronary modelbeing an anatomical structure model used to calculate the index relatingto blood flow, and perform a registration between the perfusion indexand the index relating to blood flow by identifying a relative positionof the perfusion index, the coronary artery region and the 3D coronarymodel.
 17. The medical-image processing apparatus according to claim 12,wherein the processing circuitry is further configured to perform aregistration between the blood flow image and the perfusion image, andcause the display to display a fusion image in which the blood flowimage and the perfusion image are superimposed based on a result of theregistration.
 18. A medical-image processing method performed by amedical image processing apparatus, the image processing methodcomprising: causing a display to display a combined image by combining ablood flow image representing indices relating to blood flow on acoronary artery and a perfusion image representing a perfusion index ona myocardial tissue, wherein the indices relating to blood flow areanalyzed through the coronary artery by fluid analysis on medical imagedata containing the coronary artery, the perfusion index represents adynamic behavior of blood flow passing through the myocardial tissue andis obtained by perfusion analysis on medical image data containing themyocardial tissue, obtaining an index relating to blood flow at a targetvessel of the coronary artery, determining a correspondence between thetarget vessel and the perfusion index, the perfusion index being relatedto a myocardial abnormality, calculating a treatment index indicatingnecessity of treatment for the target vessel of the coronary arteryusing the determined correspondence and the index relating to blood flowat the target vessel of the coronary artery, and causing a display todisplay the treatment index in association with the target vessel of thecoronary artery.
 19. The medical-image processing method according toclaim 18, wherein the medical image data containing the coronary arteryand the medical image data containing the myocardial tissue arecollected respectively by different types of medical-image diagnosticapparatuses.
 20. The medical-image processing method according to claim18, wherein the image processing method further comprising: analyzingthe indices relating to blood flow in the coronary artery based on thefluid analysis using the medical image data containing the coronaryartery, and analyzing the perfusion index in the myocardial tissue basedon the perfusion analysis using the medical image data containing themyocardial tissue.
 21. The medical-image processing method according toclaim 18, wherein the image processing method further comprising:extracting information of each voxel position in the medical image dataand store the information of each voxel position in a memory,identifying a position of the index relating to blood flow and aposition of the perfusion index in the medical image data based on theinformation of each voxel position, and performing a registrationbetween a surface of the myocardial tissue and the index relating toblood flow based on the position of the index relating to blood flow andthe position of the perfusion index in the medical image data.
 22. Themedical-image processing method according to claim 18, wherein the imageprocessing method further comprising: identifying a position of theperfusion index in the medical image data, identifying a positioncorresponding to a coronary artery region in the medical image data,identifying a position of a 3D coronary model in the coronary arteryregion, the 3D coronary model being an anatomical structure model usedto calculate the index relating to blood flow, and performing aregistration between the perfusion index and the index relating to bloodflow by identifying a relative position of the perfusion index, thecoronary artery region and the 3D coronary model.
 23. The medical-imageprocessing method according to claim 18, wherein the image processingmethod further comprising: performing a registration between the bloodflow image and the perfusion image, and causing the display to display afusion image in which the blood flow image and the perfusion image aresuperimposed based on a result of the registration.
 24. A medical-imageprocessing system, comprising: processing circuitry configured to causea display to display a combined image by combining a blood flow imagerepresenting indices relating to blood flow on a coronary artery and aperfusion image representing a perfusion index on a myocardial tissue,wherein the indices relating to blood flow are analyzed through thecoronary artery by fluid analysis on medical image data containing thecoronary artery, the perfusion index represents a dynamic behavior ofblood flow passing through the myocardial tissue and is obtained byperfusion analysis on medical image data containing the myocardialtissue, obtain an index relating to blood flow at a target vessel of thecoronary artery, determine a correspondence between the target vesseland the perfusion index, the perfusion index being related to amyocardial abnormality, calculate a treatment index indicating necessityof treatment for the target vessel of the coronary artery using thedetermined correspondence and the index relating to blood flow at thetarget vessel of the coronary artery, and cause a display to display thetreatment index in association with the target vessel of the coronaryartery.
 25. The medical-image processing system according to claim 24,wherein the medical image data containing the coronary artery and themedical image data containing the myocardial tissue are collectedrespectively by different types of medical-image diagnostic apparatuses.26. The medical-image processing system according to claim 24, whereinthe processing circuitry is further configured to analyze the indicesrelating to blood flow in the coronary artery based on the fluidanalysis using the medical image data containing the coronary artery,and analyze the perfusion index in the myocardial tissue based on theperfusion analysis using the medical image data containing themyocardial tissue.
 27. The medical-image processing system according toclaim 24, wherein the processing circuitry is further configured toextract information of each voxel position in the medical image data andstore the information of each voxel position in a memory, identify aposition of the index relating to blood flow and a position of theperfusion index in the medical image data based on the information ofeach voxel position, and perform a registration between a surface of themyocardial tissue and the index relating to blood flow based on theposition of the index relating to blood flow and the position of theperfusion index in the medical image data.
 28. The medical-imageprocessing system according to claim 24, wherein the processingcircuitry is further configured to identify a position of the perfusionindex in the medical image data, identify a position corresponding to acoronary artery region in the medical image data, identify a position ofa 3D coronary model in the coronary artery region, the 3D coronary modelbeing an anatomical structure model used to calculate the index relatingto blood flow, and perform a registration between the perfusion indexand the index relating to blood flow by identifying a relative positionof the perfusion index, the coronary artery region and the 3D coronarymodel.
 29. The medical-image processing system according to claim 24,wherein the processing circuitry is further configured to perform aregistration between the blood flow image and the perfusion image, andcause the display to display a fusion image in which the blood flowimage and the perfusion image are superimposed based on a result of theregistration.